A trough feeding system for poultry is for example known from U.S. Pat. No. 3,433,205 and comprises an endless feeding track meandering through a poultry stable. The track is built up out of a number of upwardly open feeding-trough segments. At their ends the segments are connected with each other by means of bend sections or corner wheels. Together the segments and the bend sections form a continuous track. The feeding-trough segments at their upper sides are each provided with a longitudinal slit-shaped feeding opening. Feed is supplied to the track out of a hopper, silo or the like. The feed is distributed over the entire track by means of pulling an endless conveying element through the track, which conveying element here is formed by an endless chain. Links of the chain are slideably supported by a bottom wall of the trough segments. The poultry is then able to pick feed out of the feeding-trough segments while standing on the floor of the stable next to one another along the feeding-trough segments.
A disadvantage herewith is that beaks of the poultry keep on growing. For some animals this may lead to difficulties during feeding. It may even make it impossible for them to quickly and easily pick feed out of the trough segments. This can for example be caused by the upper beak half growing over and passed by the lower beak half. Another disadvantage is that the growing beaks may become rather sharply pointed. On the one hand this may lead to injuries to the poultry when they start picking each other, better known as cannibalism. This leads to deteriorated feed efficiency and hen feathering during production, as well as increased mortality. On the other hand it may lead to damages to the feeding-trough segments and other parts of the feeding system inside the stable, caused by the poultry picking through them.
In addition it is noted that a continually decreasing number of countries permit beak cauterization or trimming of commercial poultry. This prohibition is introduced in connection with animal welfare. Consequently the poultry's beaks may remain razor-sharp throughout their life cycle.
Another example of a trough feeding system for poultry is known from U.S. Pat. No. 4,207,838. This system also comprises a continuous track which is formed by a number of trough segments. The endless conveying element here is formed by an endless cable with interspaced discs connected thereto. The trough segments here can be made out of metal or plastics material.
When made out of metal, it is less likely that the poultry is able to pick through the trough segments. However here also the disadvantage remains that the poultry still may have difficulties during feeding caused by malformed grown beaks, and may cause injuries to each other and to other parts of the feeding system inside the stable.
It is already known from U.S. Pat. No. 5,235,934 to have the poultry's beaks automatically get abraded and trimmed as they feed. Here it is shown to provide an abrasive surface structure on walls that delimit a feeding space inside a dispensing pan of a poultry pan feeding system. The abrasive surface is obtained by bonding small abrasive particles directly to those walls. In a variant these adhesive particles are bonded to a carrier, such as film, which is in turn adhered to the walls that delimit the feeding space inside the pan.
One drawback of this is that the adhering of the abrasive particles to the pan is difficult, since the pan is usually manufactured from polypropylene, a type of plastic that is non-glueable. A further drawback is that the granular structure of the abrasive particles varies substantially, leading to different rates at which the beaks abrade. In addition, there is a risk that some of the abrasive particles may become loose, as a result of which they may enter the feed and, consequently, the birds' stomachs. This will then, in particular, occur during a feed-restriction period in which the birds often peck in the feeder pans. The local loss of the abrasive particles will immediately result in a slower rate at which the abrading and trimming takes place. Furthermore it may lead to weak points that are susceptible to wear, and the pan may even be perforated by the birds' beaks at these points.